A simulator for sound production in airways is being proposed as a major tool for biomedical research. The work will tie together many fragmentary efforts presently ongoing in fluid mechanics, acoustics, and biomechanics of respiration and phonation. Sound production in airways is an integral part of understanding not only vocalization, but also sounds related to airway obstruction (e.g. snoring, pediatric strider, croup, and several symptoms of influenza and the common cold). In the past, researchers have focused on specific sound sources and resonators for voice and speech application, but now the entire airway will be a continuous system of potential sound sources. Specific aims are: 1) develop a two-dimensional Navier- Stokes solution for non-steady compressible air-flow in soft-walled ducts so that every airway section can potentially self-oscillate, create sound, and interact acoustically and biomechanically with any adjacent section;2) derive mathematical equivalences between lumped-element tissue models and continuum models for soft, collapsible walls;3) incorporate a muscle-activated vocal fold posturing model as a primary sound source whose material and geometric properties are determined biomechanically, and allow the location of this muscle-controlled sound source to vary along the airway;4) develop infrastructure for extending the anatomical and biomechanical properties of the airway from generic human to a variety of species, age, and gender;5) create and standardize tests for validity, accuracy, and numerical stability of simulator modules;6) design and implement a control decision center by which various levels of module complexity can be engaged. We expect that eventual experimentation with the simulation will be useful to otolaryngologists (pediatric and adult), voice and speech scientists, respiratory physiologists, speech pathologists, voice and speech trainers, and animal biologists in their interpretations of various airway phenomena. Users, based on their clinical/research needs, could select between 3 levels of input parameters to a vocal fold model: acoustic, kinematic, and physiological (muscle activation). The scientific advances will include new mathematical formulations for an airway structure that includes side branches, airway bifurcations, collapsible walls, and radiation from orifices and skin surfaces. There will also be many visualizations of air and tissue movement. Peer researchers will be contacted to submit their own modules.